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root/net/rose/rose_in.c

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DEFINITIONS

This source file includes following definitions.
  1. rose_state1_machine
  2. rose_state2_machine
  3. rose_state3_machine
  4. rose_state4_machine
  5. rose_state5_machine
  6. rose_process_rx_frame

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 *
 * Most of this code is based on the SDL diagrams published in the 7th ARRL
 * Computer Networking Conference papers. The diagrams have mistakes in them,
 * but are mostly correct. Before you modify the code could you read the SDL
 * diagrams as the code is not obvious and probably very easy to break.
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/rose.h>

/*
 * State machine for state 1, Awaiting Call Accepted State.
 * The handling of the timer(s) is in file rose_timer.c.
 * Handling of state 0 and connection release is in af_rose.c.
 */
static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        struct rose_sock *rose = rose_sk(sk);

        switch (frametype) {
        case ROSE_CALL_ACCEPTED:
                rose_stop_timer(sk);
                rose_start_idletimer(sk);
                rose->condition = 0x00;
                rose->vs        = 0;
                rose->va        = 0;
                rose->vr        = 0;
                rose->vl        = 0;
                rose->state     = ROSE_STATE_3;
                sk->sk_state    = TCP_ESTABLISHED;
                if (!sock_flag(sk, SOCK_DEAD))
                        sk->sk_state_change(sk);
                break;

        case ROSE_CLEAR_REQUEST:
                rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
                rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
                rose->neighbour->use--;
                break;

        default:
                break;
        }

        return 0;
}

/*
 * State machine for state 2, Awaiting Clear Confirmation State.
 * The handling of the timer(s) is in file rose_timer.c
 * Handling of state 0 and connection release is in af_rose.c.
 */
static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        struct rose_sock *rose = rose_sk(sk);

        switch (frametype) {
        case ROSE_CLEAR_REQUEST:
                rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
                rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
                rose->neighbour->use--;
                break;

        case ROSE_CLEAR_CONFIRMATION:
                rose_disconnect(sk, 0, -1, -1);
                rose->neighbour->use--;
                break;

        default:
                break;
        }

        return 0;
}

/*
 * State machine for state 3, Connected State.
 * The handling of the timer(s) is in file rose_timer.c
 * Handling of state 0 and connection release is in af_rose.c.
 */
static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
{
        struct rose_sock *rose = rose_sk(sk);
        int queued = 0;

        switch (frametype) {
        case ROSE_RESET_REQUEST:
                rose_stop_timer(sk);
                rose_start_idletimer(sk);
                rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
                rose->condition = 0x00;
                rose->vs        = 0;
                rose->vr        = 0;
                rose->va        = 0;
                rose->vl        = 0;
                rose_requeue_frames(sk);
                break;

        case ROSE_CLEAR_REQUEST:
                rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
                rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
                rose->neighbour->use--;
                break;

        case ROSE_RR:
        case ROSE_RNR:
                if (!rose_validate_nr(sk, nr)) {
                        rose_write_internal(sk, ROSE_RESET_REQUEST);
                        rose->condition = 0x00;
                        rose->vs        = 0;
                        rose->vr        = 0;
                        rose->va        = 0;
                        rose->vl        = 0;
                        rose->state     = ROSE_STATE_4;
                        rose_start_t2timer(sk);
                        rose_stop_idletimer(sk);
                } else {
                        rose_frames_acked(sk, nr);
                        if (frametype == ROSE_RNR) {
                                rose->condition |= ROSE_COND_PEER_RX_BUSY;
                        } else {
                                rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
                        }
                }
                break;

        case ROSE_DATA: /* XXX */
                rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
                if (!rose_validate_nr(sk, nr)) {
                        rose_write_internal(sk, ROSE_RESET_REQUEST);
                        rose->condition = 0x00;
                        rose->vs        = 0;
                        rose->vr        = 0;
                        rose->va        = 0;
                        rose->vl        = 0;
                        rose->state     = ROSE_STATE_4;
                        rose_start_t2timer(sk);
                        rose_stop_idletimer(sk);
                        break;
                }
                rose_frames_acked(sk, nr);
                if (ns == rose->vr) {
                        rose_start_idletimer(sk);
                        if (sock_queue_rcv_skb(sk, skb) == 0) {
                                rose->vr = (rose->vr + 1) % ROSE_MODULUS;
                                queued = 1;
                        } else {
                                /* Should never happen ! */
                                rose_write_internal(sk, ROSE_RESET_REQUEST);
                                rose->condition = 0x00;
                                rose->vs        = 0;
                                rose->vr        = 0;
                                rose->va        = 0;
                                rose->vl        = 0;
                                rose->state     = ROSE_STATE_4;
                                rose_start_t2timer(sk);
                                rose_stop_idletimer(sk);
                                break;
                        }
                        if (atomic_read(&sk->sk_rmem_alloc) >
                            (sk->sk_rcvbuf >> 1))
                                rose->condition |= ROSE_COND_OWN_RX_BUSY;
                }
                /*
                 * If the window is full, ack the frame, else start the
                 * acknowledge hold back timer.
                 */
                if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
                        rose->condition &= ~ROSE_COND_ACK_PENDING;
                        rose_stop_timer(sk);
                        rose_enquiry_response(sk);
                } else {
                        rose->condition |= ROSE_COND_ACK_PENDING;
                        rose_start_hbtimer(sk);
                }
                break;

        default:
                printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
                break;
        }

        return queued;
}

/*
 * State machine for state 4, Awaiting Reset Confirmation State.
 * The handling of the timer(s) is in file rose_timer.c
 * Handling of state 0 and connection release is in af_rose.c.
 */
static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        struct rose_sock *rose = rose_sk(sk);

        switch (frametype) {
        case ROSE_RESET_REQUEST:
                rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
        case ROSE_RESET_CONFIRMATION:
                rose_stop_timer(sk);
                rose_start_idletimer(sk);
                rose->condition = 0x00;
                rose->va        = 0;
                rose->vr        = 0;
                rose->vs        = 0;
                rose->vl        = 0;
                rose->state     = ROSE_STATE_3;
                rose_requeue_frames(sk);
                break;

        case ROSE_CLEAR_REQUEST:
                rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
                rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
                rose->neighbour->use--;
                break;

        default:
                break;
        }

        return 0;
}

/*
 * State machine for state 5, Awaiting Call Acceptance State.
 * The handling of the timer(s) is in file rose_timer.c
 * Handling of state 0 and connection release is in af_rose.c.
 */
static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        if (frametype == ROSE_CLEAR_REQUEST) {
                rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
                rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
                rose_sk(sk)->neighbour->use--;
        }

        return 0;
}

/* Higher level upcall for a LAPB frame */
int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
{
        struct rose_sock *rose = rose_sk(sk);
        int queued = 0, frametype, ns, nr, q, d, m;

        if (rose->state == ROSE_STATE_0)
                return 0;

        frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);

        switch (rose->state) {
        case ROSE_STATE_1:
                queued = rose_state1_machine(sk, skb, frametype);
                break;
        case ROSE_STATE_2:
                queued = rose_state2_machine(sk, skb, frametype);
                break;
        case ROSE_STATE_3:
                queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
                break;
        case ROSE_STATE_4:
                queued = rose_state4_machine(sk, skb, frametype);
                break;
        case ROSE_STATE_5:
                queued = rose_state5_machine(sk, skb, frametype);
                break;
        }

        rose_kick(sk);

        return queued;
}

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